It is well known to produce thermoplastic fluid containers from thermoplastic preforms. Generally, these thermoplastic preforms are produced by injection molding. These preforms produced by injection molding generally have a rounded closed end and a cylindrical open end.
During injection molding of large quantities of preforms, it is inevitable that a number of the preforms produced will be defective. A number of different types of defects are possible. For example, if an insufficient amount of thermoplastic is injected into the mold a preform having an irregular and insufficient cylindrical open end will be formed. A preform having a defective open end due to the insufficient injection of thermoplastic material is often termed a "short shot." Another common defect occurs when too much thermoplastic material is injected and excess material is formed at the closed end of the preform.
Yet another type of defect can occur when there is insufficient cooling of a preform before it is ejected out of the mold. A preform having an irregular open end with some of the thermoplastic material pushed inwardly toward the center of the open end can result from such insufficient cooling prior to ejection.
Any fluid container manufactured from a defective preform will also be defective. Heretofore it has been common practice to manually inspect preforms or to perform no inspection of the preforms at all prior to manufacturing the preforms into fluid containers. Manual inspection of these preforms is time consuming and inexact. It is difficult by manual and visual inspection only to determine, for example, if the internal neck size of a preform is correct. Thus, previous manual inspection techniques resulted in defective preforms being manufactured into defective fluid containers. In addition, manual inspection of preforms is labor intensive and costly. However, if the preforms are not inspected prior to manufacturing the preforms into finished fluid containers, it is highly likely that many defective fluid containers will be produced.
It is therefore an object of the present invention to provide preform handling apparatus which is free of the disadvantages of known methods for orienting and testing preforms.
It is another object of the present invention to provide preform handling apparatus which automatically orients and tests a plurality of preforms for defects.
It is yet another object of the present invention to provide preform handling apparatus capable of properly aligning a plurality of randomly oriented preforms.
It is a further object of the present invention to provide a preform handling apparatus for automatically testing a plurality of preforms for a variety of defects.
It is still another object of the present invention to provide a preform handling apparatus capable of orienting and testing a plurality of preforms without the need for human intervention.
It is a still further object of the present invention to provide preform handling apparatus which automatically inverts preforms by rotating the preforms 180.degree..